A variety of automated systems currently exist for controlling blinds, drapery, and other types of window coverings. These systems often employ photo sensors to detect the visible light (daylight) entering through a window. The photo sensors may be connected to a computer and/or a motor that automatically opens or closes the window covering based upon the photo sensor and/or temperature read-out.
While photo sensors and temperature sensors may be helpful in determining the ideal shading for a window or interior, these sensors may not be entirely effective. As such, some shade control systems employ other criteria or factors to help define the shading parameters. For example, some systems employ detectors for detecting the angle of incidence of sunlight. Other systems use rain sensors, artificial lighting controls, geographic location information, date and time information, window orientation information, and exterior and interior photo sensors to quantify and qualify an optimum position for a window covering. However, no single system currently employs all of these types of systems and controls.
Moreover, most automated systems are designed for, and limited for use with, Venetian blinds, curtains and other traditional window coverings. Further, prior art systems generally do not utilize information related to the variation of light level within the interior of a structure. That is, most systems consider the effects of relatively uniform shading and/or brightness and veiling glare, rather than graduated shading and/or brightness and veiling glare. Therefore, there is a need for an automated shade control system that contemplates graduated shading and optimum light detection and adaptation.
It has been determined that the most efficient energy design for buildings is to be able to take advantage of natural daylight which allows for the reduction in artificial lighting which in turn reduces the Air Conditioning load, which reduces the energy consumption of a building. To achieve these goals, the glazing has to allow a high percentage of daylight to penetrate the glazing, by using clear or high visible light transmitting glazing. But with the high amount of visible light there is also the bright orb of the sun, excessive heat gain, and debilitating solar rays which will at different times of the year and on different solar orientations penetrate deeply into the building, effecting and impacting the persons working or living therein. Thus, a need exists to manage and control the amount of solar load, solar penetration, and temperatures of the window wall. In addition, there is a need to control the amount of solar radiation and brightness to acceptable norms that protect the comfort and health of the occupants, e.g. an energy conserving integrated subsystem.